Sander



March 3, 1964 v. L. FRANTZ 3,123,386

SANDER Filed Dec. 29, 19e1 2 Sheets-Sheet l FIG. 3

J In v e n to r Virgil L. Frantz his Attorney March 3, 1964 Filed Dec.29, 1961 Q I C) I8 I 20 k -2/ H 25 I- H i 4 a 24 5 I I 36 H 23 6a i 24 II 25 LLE 2/ FIG. 4

FIG. 5

v. L. FRANTZ 3,123,386

SANDER 2 Sheets-Sheet 2 FIG. 7

FIG. 8

Virgil L. Frantz YWMM his Attorney United States Patent 3,123,386 SANDERVirgil L. Frantz, Salem, Va., assignor to Graham-White SalesCorporation, Salem, Va., a corporation of Virginia Filed Dec. 29, 1961,Ser. No. 163,312 21 Claims. (Cl. 2.9111) This invention relates tosanders for locomotive and like sanding systems and has for its primaryobject the provision of an improved sander whereby the quantity of sandapplied during a sanding operation of a given duration is adjustableover a wide range and to suit sands of difi'erent characteristics.

Another object of the invention is to provide an improved sander bywhich the rate of discharge of sand during a sanding operation isregulatable independently of the pressure of the actuating air.

An additional object of the invention is to provide an improved sanderwherein the actuating air is admixed without turbulence with the sand,thereby eliminating any cutting action by the sand whether the admixingis within or beyond the sander.

A further object of the invention is to provide a sander wherein thesand flows by gravity at a regulated rate from a sand chamber to thepoint of admixture with actuating air and is discharged from the chamberwithout being subjected therein either to turbulence or to suction bythe air, thereby enabling the rate of discharge of the sand to beregulated with a preciseness heretofore unobtainable.

Another object of the invention is to provide an improved sander of sucharrangement and construction that its clean-out port can be opened andclosed without interference by sand in the body thereabove.

A further object of the invention is to provide in a sander a clean-outplug which is readily applied and removed without use of tools, ispractically foolproof and is eifective to seal the clean-out portagainst leakage.

Other objects and advantages of the invention will appear hereinafter inthe detailed description, be particularly pointed out in the appendedclaims and be illustrated in the accompanying drawings in which:

FIGURE 1 is a side elevational view of a preferred embodiment of thesander of the present invention;

FIGURE 2 is a front elevational View of the sander of FIGURE 1;

FIGURE 3 is a vertical sectional view on an enlarged scale taken alonglines 33 of FIGURE 2;

FIGURE 4 is a view of the sander partly in top plan and partly in ahorizontal section taken along lines 44 of FIGURE 1;

FIGURE 5 is a bottom plan view of the sander of the preceding figures,showing the locking mechanism for the clean-out plug in lookingposition;

FIGURE 6 is a fragmentary bottom plan view showing the locking mechanismfor the plug in release position;

FIGURE 7 is a horizontal sectional view taken along lines 7-7 of FIGURE1; and

FIGURE 8 is a horizontal sectional view taken along lines 8-8 of FIGURE1.

Referring now in detail to the drawings in which like referencecharacters designate like parts, the improved sander or sand trap of thepresent invention is similar to those of my copending applications,Serial Nos. 774,235, filed November 17, 1958, now Patent No. 3,020,072,and 43,225, filed July 15, 1960, now Patent No. 3,088,764, incontrolling the rate at which the sand is discharged by the actuatingair by regulating the rate at which the sand flows to the point ofadmixture with the air. Too, in this and the copending applications,regulation of the rate of flow of the sand to the point of admixturewith the air 3,123,386 Patented Mar. 3, 1964 is exercised by providingin the sander a layer or mound of sand, the upper surface of whichslopes toward the outlet end of the sand chamber at the gradient orslope fixed by the angle of repose of the particular sand and, byvarying the height of that surface above the floor of the sand chamber,correspondingly varying the quantity of sand available for mixing withthe air in any given operating cycle. However, although basicallysimilar to the sanders of the prior applications, the sander of thisinvention is capable of controlling the discharge of the sand with apreciseness heretofore unobtainable and improves upon the earliersanders in numerous further respects.

In the preferred embodiment illustrated in the accompanying drawings,the sander of this invention is comprised of a body 1, generally ofL-shape, with angularly related inlet and outlet legs 2 and 3, the inletor upper and outlet or front ends 4 and 5, respectively, of which areflanged or otherwise suitably fitted for connection of the inlet end toan overlying sand dome or reservoir (not shown) and of the outlet endeither directly or through an extension indicated at 6 to a dischargepipe (not shown). Contained in the body 1 is a sand chamber 7 havingconnected, angularly related inlet and outlet legs 8 and 9, the formergenerally vertically disposed within the correspondingly disposed inletleg 2 of the body and terminating upwardly in an inlet port or inlet orupper end 10 opening upwardly onto the corresponding end 4 of the inletleg 2 of the body. In turn, the outlet leg 9 of the sand chamber 7extends generally in a horizontal direction into the bodys outlet leg 3and terminates out Wardly in an outlet port or outlet or outer end 11.While the bodys outlet leg 3 may extend beyond the outlet end 11 of thesand chambers outlet leg 9, as by making the extension 6 integral withthe body, it ordinarily will be preferred that, as in the illustratedembodiment, the chambers outlet leg project or extend through and becoterminous with the bodys outlet leg. However, Whether it opens withinor at the end of the body, the outlet leg 9 of the sand chamber shouldopen onto a smooth, uninterrupted bore 12, such as that of the extension6.

In a conventional sand trap, sand is fed by gravity into a sand chamber7 from a sand dome and during a sanding operation an air jet is applieddirectly on the sand in the chamber to discharge it into the associateddischarge pipe. Since variation in the pressure of the ac tuating airhas little eifect upon the rate of discharge, the result is that thequantity of sand discharged in a sanding operation depends entirely onthe duration of that operation. This conventional action has three mainundesirable attributes, one that, with the rate of dischargeuncontrollable, it is practically impossible for the operator to gaugethe quantity of sand applied, another that it makes no allowance for thedifference in flow characteristics between sands of different types, andthe third that the abrasive action of the sand blast generated in theinterior of the trap drastically curtails its service life. None ofthese undesirable attributes is possessed by the sander of thisinvention. Instead, the sand and air are mixed outside the sand chamberand the sand flows out of the chamber of admixture with the air at aregulated rate which in turn controls its rate of discharge through thedischarge pipe.

With sand fed by gravity through the inlet port 10 from the overlyingsand dome and normally substantially filling the inlet leg 8 of the sandchamber, the rate of flow of the sand through the outlet leg 9 in asanding operation is regulated by a blade or paddle 13 disposed orcontained in the body 1 above the connecting passage 14 between theinlet and outlet legs and swingable, oscillatable, slL'ftable or movableto vary its vertical spacing from or above the underlying portion of thefloor 15 of the sand chamber and thus the height of the connectingpassage. In its preferred form, the blade 13 has a hub 16 which isintegral with and extends between a pair of cylindrical discs 17received and rotatable in apertures 18 in the opposite side walls 19 ofthe body 1 and of a diameter radially to contain the blade so as topermit the latter to be applied and removed through either aperture.Each of the discs 1'7 preferably carries in a peripheral groove 2%} anO-ring 21 which serves both to seal its joint with its aperture 18 and,by trictionally resisting relative rotation, hold the blade in theposition in which it is set.

For locking the blade 13 against axial shifting, as well as to preventseepage of sand above it into the outlet leg 9, there is provided ashield or looking plate 22 screwed or otherwise releasably attached tothe adjoining or overlying front wall 23 of the inner leg 8 and benttherebelow as necessary to extend downwardly substantially to the centeror rotative axis of the discs 17. Of substantially the width of theblade 13, at least over its portion contained between the discs 17, theshield 22 preferably has on either side of that portion ears 24-, whichconveniently are sectoral and of substantially the radius of the discsand, by rubbing against the latter, aid or augment the frictional actionof the O-rings 21 in positioning the blade. However, the main purpose ofthe ears Z4 is to enable the shield 22 positively to stop the blade 13at the opposite limits of its swing or oscillation. This conveniently isaccomplished by providing on the side walls 19 of the body 1 along therear portions of the apertures 13 a pair of instanding, integral orfixed abutments 25, each of which is engaged by one of the cars 24, bydisposing the bottom. edges of the ears in a position to be engaged bythe leading face 27 of the blade 13 at the lower limit of the lattersswing and by forming on the hub la? of the blade a lug or upsetengageable with the rear face of the shield at the opposite or upperlimit of the blades swing. With this arrangement, the blade not only ispositively limited. in the extent of its swinging, oscillating orshifting movement relative to the body 1' but, within those limits, iseffectively held by friction in any position in which it is set;Further, the particular position in which the blade is set or adjustedis readily made visually determinable by providingapointer fixed to andon or in the outer face of one of the end discs and a scale 3%? etchedor otherwise formed on the body alongside that disc. Also, tamperingwith the settin or adiustrnent of the blade is readily prevented bymaking the blade adjust ble only by a special tool suitably a socketwrench (not shown) fit table into a hex socket 31 extending through thehub 16 andthe discs 17 of the blade unit.

To make maximum use of the adjustability in the rate of flow of sand,through the outlet leg 9 of the sand chamher 7 made possible by theblade, it is essential that the upper surface 32 of the sand mound inthe outlet leg 9 be unobstructed beyond the blade and, to facilitatecalibration, desirable that the bottom edge 33 of the blade be straightand horizontal and transversely parallel to the underlying portion ofthe floor 15 of the sand chamber 7. To the same end, it also isdesirable that the spaced sides 3 of the outlet'port ll. be straightextend upwardly at the same angle from the lip or outer edge 35 of thefloor and that the lip be straight and horizontal. The desirability ofhoriz "itality in the lip 35 or": the floor at the outlet end ll of theoutlet leg i does not require that the floor in advance of-the lip alsobe horizontal. n the contrary, it is desirable that the door siopedownwardly toward the lip to minimize the accumulation and possibleclogging of sand within the sand chamber and only necessary that theslope of the floor within the outlet leg 9 be less than the angle ofrepose of any sand that might be used in the sander so as not tooverride the regulation of the rate of flow by the blade.

With the above necessary and desirable limitations, the

elative vertical spacing or disposition of the bottom or lower edge 33of the blade 13 and the lip 35 of the floor 15' is determinative of thedepth in repose of the layer or stratum oi sand in the outlet leg 9 atany point along the door beyond the blade. Thus, with the sides andbottom of the sand layer fixed by the floor 15 and sides 34 of theoutlet leg, the relative position of the blade, by regulating the depthof the layer in advance of and at the lip, will control the quantity ofor rate at which the sand can flow by gravity past the lip when theequilibrium or repose is upset so that the sand can flow freely.Consequently, by mixing the sand with the actuating air beyond the sandchamber 7 and fiixing the limits of adjustment of the blade 13 suchthat, over the range of angles of repose of the various types of sandused in sanding, the depth of the sand in repose above the lip 35 willbe zero at one limit and at maximum at the other, it should be possiblefor the blade to be set either to cut olf the sand entirely or toregulate precisely or exactly the quantity discharged during a sandingoperation of a given duration, in all cases by varying the height of butnever closing the connecting passage in the sand chamber. However, whilethis objective is approached in the sander of application Serial No.43,225, it has not heretofore been attained because of the inability toeliminate entirely the action of the actuating air within the outlet leg9, at least in the form of suction, and the consequent interference withthe desired true, pure or unadulterated gravity flow of sand from thesand chamber.

It has now been discovered that the desired true gravity flow of sandfrom the sand chamber 7 can be obtained and this discovery has beenincorporated in its preferred practical form in the disclosed embodimentof the sander of this invention. There were two main keys to thisdiscovcry. One was as to the pressure of the actuating air. Heretofore,it has been thought that to convey sand from a sander throughthe'discharge pipe to the rails required to be applied to the sand atthe sander at pressures on the order of 5 p.s.i. Consequently, with theline pressure available in the usual locomotive at the valve controllingthe sanding operation ranging from -140 p;s.i., the size of t e sandingorifice in the control valve conventionally is made such-as to deliverair to the sandtrapat a pressure of around 5 psi. Contrary to such priorthinking, it has now been found that when, as here, the sand and air aremixed beyond the sand chamber, the sand can be conveyed effectively tothe rail surface by air at a pressure at the air outlet of aroundlp.s.i. and that at such low pressure the actuating air will exert nosuction on the sand in the sand chamber.

The other key was the discovery that it was possible to eliminateturbulence in the chamber in which the sand and air were mixed, here thebore 12, and consequent possible disturbance of the sand within the sandchamber, by injecting the air stream into the mixing chamber not onlybelow the outlet port 11 of the sand chamber but also over the fullwidth of the chamber or at least over a width that covered, embraced orincluded the lateral limits of the sand outlet or outlet portion 11a ofthe outlet port 11 occupied or tilled by sand at the maximum flowsetting of the blade l3. With the air stream thus at least coextensivelaterally of transversely with the overlying sand outlet 11, the effectis that, as the sand is'discharged from the outlet, it drops or fallsonto and not through the stream or curtain of actuating air and withoutturbulence is mixed with the air and carried thereby to the outlet endof the discharge pipe.

The reduction in the pressure of the air to the desired low level 18 notreadily obtainable by a f irther reduction in the size of the alreadysmall orifice in the associated control valve, nor is such amodification desirable without standardization upon a sander operable atsuch a low pressure. Practically, the desired low pressure shouldtherefore be obtained by a further reduction at the sander of thepressure of the air delivered thereto from the control valve.Conceivably, this could be accomplished by use of a nozzle of specialconstruction releasably mounted in the body 1, but it is simpler andpreferred to build or form an air passage of the desired characteristicsas an integral part of the body. In accordance with the preferredconstruction, the body 1 has at the rear adjacent the bottom of itsinlet leg 2 an air inlet port 36 conveniently tapped for connection ofthe line (not shown) from the associated control valve and openinginwardly onto an air passage or conduit 37 in the bottom wall 38 of thebody below the floor of the sand chamber 7. The air passage 37 adjacentthe inlet port 36 preferably branches around a clean-out port 39extending vertically through the bottom wall 38 and opening upwardlytoward the inlet leg 8 of the sand chamber 7, suitably as opensidedchannels or grooves 4G in the side 41 of the cleanout port. Beyond theclean-out port 39, the air passage 37 increases very substantially incross-section to provide an expansion chamber 42, the cross-sectionalarea of which, for applications of the sander to the usual locomotivesystem, is desirably about three times the free cross-sectional areaoccupied by the air as it enters the inlet port. Once increased, thecross-sectional air of the air passage remains substantially uniform toand including the air outlet or outlet port 43. As shown in FIGURE 2,the air outlet is laterally or horizontally elongated or flattened andnot only parallels and includes the lateral limits of the lip 35 of theoutlet port 11, but, to eliminate possible turbulence at the sides,extends substantially the full width of or is substantially coextensivewith the portion of the bore or mixing chamber 12 onto which it opens.By contrast, the sand outlet lie, the lip 35 bounding the bottom ofwhich in the illustrated embodiment lies substantially along a diameterof the cylindrical mixing chamber 12, is held within the lateral boundsof the air outlet conveniently by downwardly tapering or converging thesides 34 of the outlet port 11.

An important feature of the sander of the present invention is itsability to have its clean-out port opened for cleaning out the hollowinterior of the body and closed for a sanding operation, both withoutthe use of tools. Conventionally, the clean-out port of a sand trap isclosed by a metal plug threaded into the port and applied and removed bya suitable wrench which quite often is not handy. In marked contrast,the preferred cylindrical clean-out port 39 is of uniform cross-sectionand smoothbored except for the interruption of its side or side wall llby the parts of the air passage 37 opening thereonto and the relatedplug 4-6 is slidable axially into its seat in the bore and lockabletherein by a simple manipulation of actuating means attached to it.

In its preferred form, the plug 4d includes a rigid cylindrical stem,post or centerpiece 47 having fixed to or integral or rigid with itsupper end an enlarged head or peripheral flange 48, the stem being ofless and the head of substantially the same diameter as the port.Surrounding or encircling and preferably slidably received on the stem47 below and abutting against the underside of the head 48 is a rubberor like compressible cylindrical sleeve 4-9, the outside diameter ofwhich, in uncompressed or free condition, is substantially that of theport, so that the sleeve in that condition, as Well as the head, canreadily or freely be slid into the port. The stem 47 is of greaterlength or axial extent than the sleeve 49 and therebelow is slidablyencircled by a washer 55 which, unlike the head and sleeve, is of toogreat diameter to fit into the port and, instead, is designed to engagethe lower end of the sleeve and the surrounding underside of the bottomwall 38 of the body 1.

With the sleeve 49 contained, embraced or straddled axially by the head48 and the washer 5t and the head and sleeve slid into the port 39 tothe point at which the washer engages the bottom wall as, an inwardaxial force on the head and washer will compress or squeeze the sleeveand, by causing it to expand inwardly and outwardly against theconfronting sides of the port and stem and to bulge into the exposedparts of the air passage 37,

not only will seal the port and the air passage but will lock the plugin the port. The necessary inward axial force is here applied by anoperating handle 51 pivotally mounted below the sleeve on radialtrunnions 52 carried by the stem 47 which, for ready application andremoval of the sleeve and washer, preferably are the diametricallyopposed ends of a pin driven radially through the stem. While theprojecting arm 53 of the handle 51 provides the necessary leverage, theinward axial force is derived from a pair of integral cams 54 on thehandle, one on either side of the stem. The cams 54 ride against theunderor confronting face of the washer 50 and their shape is such that,when the arm 53 is swung downwardly to a sub stantially vertical releaseposition, the sleeve is uncompressed, while on swinging of the armupwardly, they act through the washer against the bottom wall 38 of thebody 1 and through the stem 47 on the head 48 to pull the latterdownwardly toward the washer until, when the arm is in its substantiallyhorizontal locked position, the sleeve has been compressed to the extentnecessary to seal the port and the exposed sides of the air passage 37.

For locking the handle in locking position so as to prevent it frombeing jarred to release position by service shocks, catch means arefixed to or made rigid with the underside of the washer Ell, preferablyin the form of a pair of circumferentially spaced catches 55 under oneor the other of which the arm 53 can slide and be locked on being swunghorizontally in that direction, the spaced catches having the advantageover a single catch of accommodating the locking means to the exigenciesof different installations. Additionally, to ensure that the arm 53,when swung to locked position, will be in a position to engage eithercatch 55, there are fixed to and formed integrally with the earns 54, ata side of the pivot opposite the arm, a pair of oppositely outstandingpositioning lugs 56 which, when the handle 53 is swung downwardly, swingbetween a pair of preferably flat inner-sided detents or guides 57 fixedto and depending from the underside of the washer and here forming thebase portions of the catches. By engagement with the detents 57, thepositioning lugs 56 prevent the handle from being rotated when it is inunlocked position and ensure the proper positioning of the arm 53relative to the catches 55 when the handle is swung upwardly to closedposition.

With the combined axial extent of the head 48 and the sleeve 49 incompressed condition preferably substantially equal to the thickness ofthe bottom wall 38 of the body l, the upper surfaces of the plug 46 andthe bottom wall will be substantially on a level when the plug is lockedin the clean-out port 39 and that of the plug might then serve as partof the floor 15 of the sand chamber 7. However, in the absence of somemeans of cutting off sand from the sand chamber, a difiiculty would beposed in so applying the plug as to assure that there were no sandparticles between it and the side 41 of the port. This difficulty isavoided by mounting in the body 1 above the clean-out port 39 a rubberor like flexible or distortable flap 58 normally closing off the outletport from the sand chamber 7. Conveniently supported at one end on ashoulder 59 on the rear wall tl of the body 1 instanding into the inletleg 8 of the sand chamber and screwed or otherwise fixed at that end tothe body, the flap preferably is tapered toward its free end and restsat that end on the underlying portion of the floor 15 of the sandchamber in the area below the blade 13.

With an integral depending pull 61 conveniently normally received in arecess 62 in the upper portion of the stem 47 of the plug 46 andinstanding, overlying stops 63 on the side Walls 19 to fix its normalposition, the flap on removal of the plug may be pulled down into theclean-out port 39 to enable the interior of the sander to be cleanedtherethrough and, when pushed back into its normal place or positionabove the clean-out port, will effectively hold the sand thereabove andprevent interference with reapplication of the plug. Too, by sloping theflap in normal posiamass-s tion downwardly toward the outlet end ll ofthe sand chamber '7 substantially in correspondence with the slope ofthe adjoining portion of the floor 15, the flap 58 in that position notonly forms the part of the floor underlying the inlet leg 55 butminimizes the chance that sand will accumulate and become clogged at thebottom of that leg.

From the above detailed description, it is apparent that there has beenprovided an improved sander which is capable of regulating exactly theamount of sand applied during a sanding operation, of long service lifeand readily maintained in operating condition. It should be understoodthat the described and disclosed embodiment is merely exemplary of theinvention and that all modifications are intended to be included whichdo not depart from the spirit of the invention or the scope of theappended claims.

Having escribed my invention, 1 claim:

1. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, blade means shiftablymounted in said body within said chamber for regulating the depth ofsand in said outlet leg and therethrough the rate of discharge of sandby gravity from an outlet of said chamber, and an air outlet in saidbody below and at least coextensive laterally with said sand outlet,said outlets opening beyond said sand chamber onto a mixing chamber inwhich said sand and air are mixed during a sanding operation.

2. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, blade means shiftablymounted in said body within said chamber for regulating the depth ofsand in said outlet leg and therethrough the rate of discharge of sandby gravity from an outlet of said chamber, an air outlet in said bodybelow and at least coextensive laterally with said sand outlet, saidoutlets opening beyond said sand chamber onto a mixing chamber in whichsaid sand and air are mixed during a sanding operation, and an airpassage in said body in advance of said air outlet and including anexpansion chamber for reducing the pressure of the air applied to saidsander before injection thereof into said mixing chamber.

3. A sander comprising a body, a sand chamber in said body havingconnected angularly related inlet and outlet legs, blade means shiftabiymounted in said body within said chamber for regulating the depth ofsand in said outlet leg and therethrough the rate of discharge of sandby gravity from an outlet of said chamber, an air outlet in said bodybelow and at least coextensive laterally with said sand outlet, saidoutlets opening beyond said sand chamber onto a mixing chamber in whichsaid sand and air are mixed during a sanding operation, an air passagein said body in advance of said outlet outlet, and means in said passagefor reducing the pressure of air passing therethrough prior to injectionthereof into said mixing chamber.

4. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, blade means shiftablymounted in said body within said chamber for regulating the depth ofsand in said outlet leg and therethrough the rate of discharge ofsaid bygravity from an outlet of said chamber, and a laterally elongated airoutlet in said body below and at least coextensive laterally with saidsand outlet, said outlets opening beyond said sand chamber onto a mixingchamber in which said sand and air are mixed during a sanding operation.

5. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outleg legs, blade means shiitablymounted in said body within said chamber for regulating the depth ofsand in said outlet leg and therethrough the rate of discharge of sandby gravity from an outlet of said chamber, a laterally elongated airoutlet in said body below and at least coextensive laterally with saidsand outlet, said outlets opening beyond said sand chamber onto a mixingchamber and at least coextensive laterally in which said sand and airare mixed during a sanding operation, and an air passage in said body inadvance of said outlet and including an expansion chamber of increasedcross-section for reducing the pressure of air passing therethrough inadvance of injection thereof into said mixing chamber.

6. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, blade means shiftablymounted in said body within said chamber for regulating the depth ofsand in said outlet leg and therethrough the rate of discharge of sandby gravity from an outlet of said chamber, a laterally elongated airoutlet in said body below said sand outlet, said outlets opening beyondsaid sand chamber onto a mixing chamber in which said sand and air aremixed during a sanding operation, said air outlet laterally includingsaid sand outlet and being coextensive with said mixing chamber, and anair passage in said body in advance of said air outlet and including anexpansion chamber of substantially the cross-section of said air outletand increased cross-section relative to an air inlet thereto forreducing the pressure of air passing therethrough in advance ofinjection thereof into said mixing chamber.

7. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, blade means swingablymounted in said sand chamber for regulating the depth of sand in saidoutlet leg, means fixed to said body and engageable with said blademeans at opposite limits of the swinging thereof for positively fixingsaid limits, and an air outlet in said body below and at leastcoextensive laterally with said sand outlet, said outlets opening beyondsaid sand chamber onto a mixing chamber in which said sand and air aremixed during a sanding operation.

8. A sander comprising a'body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, a sand outlet fromsaid chamber at an outlet end of said outlet leg, a blade unit rotatablymounted in said body, said unit including a blade shiftable within saidsander for varying the depth of sand in said outlet leg, discs atopposite ends of said blade and rotatably seated in apertures in sidesof said body, and friction means between said discs and body foryieldably resisting rotation of said unit, a shield releasably attachedto said body above said unit and extending downwardly between said discfor preventing axial movement thereof, means on and projecting from saidshield and engageable with instanding abutment means fixed to said body,said shield and projecting means being engageable with said blade atopposite limits of shifting thereof and positively fixing said limits byengagement of said projectingmeans with said abutment means, saidprojecting means frictionally engaging said discs for aiding saidfriction means in yieldably resisting rotation of said blade unit, andan air outlet in said body below with said sand outlet, s id outletsopening beyond said sand chamber onto a mixing chamber in which saidsand and air are mixed during a sanding operation.

9. A sander comprising a body, a sand chamber in said body and havingconnected inlet and outlet legs, a sand outlet from said chamber into amixing chamber, a smooth-bored clean-out port in a bottn wall of saidbody and opening upwardly toward said inlet leg, an

air passage in said body and having an outlet onto said mixing chamberbelow and at least coextensive laterally with said sand outlet, saidhaving portions opening at sides onto and interrupting a side of saidport, and a clean-out plug slidable axially into said port, said plugincludin-" a compressible sleeve slidable in uncom pressed conditionfreely into said port and over s id sides of said portions, and meansfor a co ipressing s d sleeve within said port and said sides of saidpassage portions and thereby sealing said port and locking said plug insaid port.

'10. A sander comprising a body, a sand. chamber in said body and havingangularly related inlet and outlet legs, means for regulating the rateof discharge of sand from said chamber during a sanding operation, acleanout port in said body below and opening upwardly toward said inletleg, a plug slidable axially into said port, said plug including acompressible sleeve slidable in uncompressed condition into said port, astem in said sleeve, a flange fixed to an upper end portion of said stemand overlying an upper end of said sleeve and slidable therewith intosaid port, a washer slidably encircling said stem below said sleeve andengageable with a lower end thereof and an underside of said body, cammeans carried by said stem below and actable against said washer and onsaid flange means for compressing said sleeve therebetween and therebysealing said port and locking said plug therein, an arm rigid with saidcam means for swinging thereof to locking and release positions, andcatch means depending from said washer and engageable with said arm inthe locking position of said cam means for locking said cam means insaid position.

ll. A sander comprising a body, a sand chamber in said body and havingangularly related inlet and outlet legs, means for regulating the rateof discharge of sand from said chamber during a sanding operation, acleanout port in said body below and opening upwardly toward said inletleg, a plug slidable axially into said port, said plug including acompressible sleeve slidable in uncompressed condition into said port, astem in said sleeve, a flange fixed to an upper end portion of saidstern and overlying an upper end of said sleeve and slidable therewithinto said port, a washer slidably encircling said stem below said sleeveand engageable with a lower end thereof and an underside of said body,cam means carried by said stem below and actable against said washer andon said flange means for compressing said sleeve therebetween andthereby sealing said port and locking said plug therein, an arm rigidwith said cam means for swinging thereof to locking and releasepositions, and a pair of circumferentially spaced catches fixed to anddepending from said washer and alternately engageable with said arm onswinging thereof in the locking position of said cam means for lockingsaid cam means in locking position.

12. A sander comprising a body, a sand chamber in said body and havingangularly related inlet and outlet legs, means for regulating the rateof discharge of sand from said chamber during a sanding operation, aclean out port in said body below and opening upwardly toward said inletleg, a plug slidable axially into said port, said plug including acompressible sleeve slidable in uncompressed condition into said port, astem in said sleeve, a flange fixed to an upper end portion of said stemand overlying an upper end of said sleeve and slidable therewith intosaid port, a washer slidably encircling said stem below said sleeve andengageable with a lower end thereof and an underside of said body, cammeans carried by said stem below and actable against said washer and onsaid flange means for compressing said sleeve therebetween and therebysealing said port and locking said plug therein, an arm rigid with saidcam means for swinging thereof to locking and release positions, a pairof circumferentially spaced catches fixed to and depending from saidwasher and alternately engageable with said arm on swinging thereof inthe locking position of said cam means for locking said cam means inlocking position, and means on said cam means and engageable with meanson said washer on swinging of said cam means to unlocking position forlocating said arm between said catches on swinging of said cam means tolocking position.

13. A sander comprising a body, a sand chamber in said body and havingangularly related inlet and outlet legs, means for regulating the rateof discharge of sand from said chamber during a sanding operation, aclean- 10 out port in said body below and opening upwardly toward saidinlet leg, a plug insertable in said port, and a flexible flap withinsaid body above and normally shutting off said port from said sandchamber, said flap on removal of said plug being pullable into said portfor enabling the interior of said body to be cleaned.

14. A sander comprising a body, a sand chamber in said body and havingangularly related inlet and outlet legs, means for regulating the rateof discharge of sand from said chamber during a sanding operation, acleanout ort in said body below and opening upwardly toward said inletleg, a plug insertible in said port, a flexible rubber flap within andfixed at one end to said body above said port and normally shutting offsaid port from said sand chamber, and a pull depending from said flapand normally received in an upwardly opening recess in said plug, saidflap on removal of said plug being pullable by said pull into said portfor cleaning of the interior of said body.

15. A sander comprising a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, a smooth-boredclean-out port opening upwardly through a bottom wall of said bodytoward said inlet leg, groove means extending transversely andinterrupting a side of said here, a plug including a COID- pressiblerubber sleeve slidable in uncompressed condition axially into said port,means for compressing said sleeve axially and thereby sealing said portand by bulging of said sleeve into said groove means locking said plugin said port, a flexible rubber flap within and fixed at one end to saidbody above and normally shutting off said port from said sand chamber,and a pull depending from said flap and normally received in an upwardlyopening recess in said plug, said flap on removal of said plug beingpullable by said pull into said port for cleaning of the interior ofsaid body.

16. A sander comprising a body, a sand chamber in said body and havingan outlet, means in said body for controlling the rate of discharge ofsand by gravity from said outlet, an air outlet in said body below saidsand outlet, said outlets opening beyond said sand chamber onto a mixingchamber in which sand and air are mixed during a sanding operation, anair passage in said body in advance of said outlet, and means in saidpassage for reducing the pressure of air passing therethrough prior toinjection thereof into said mixing chamber.

17. A sander comprising a body, a chamber in said body for receivingsand, a passage for delivering air for mixing with sand received in saidbody, and an expansion chamber in said passage for reducing the pressureof air passing therethrough prior to mixing thereof with said sand.

18. A sander comprising a body, a chamber in said body for receivingsand, an air passage in said body and connectable to an air supply lineleading thereto for delivering air for mixing with sand received in saidcham her, and means interposed between said supply line and an outlet ofsaid passage for reducing relative to the pressure in said supply linethe pressure of the air delivered through said passage.

19. A sander comprising a body, a sand chamber in said body and havingconnected inlet and outlet legs, a sand outlet from said chamber into amixing chamber, a smooth-bored clean-out port in a bottom wall of saidbody and opening upwardly toward said inlet leg, an air passage in saidbody and having an outlet onto said mixing chamber below said sandoutlet, said passage having portions opening at sides onto andinterrupting a side of said port, and a clean-out plug slidable axiallinto said port, said plug including a compressible sleeve slidable inuncompressed condition freely into said port and over said sides of saidpassage portions, and means for axially compressing said sleeve withinsaid port and thereby sealing said port and said sides of said passageportions and locking said plug in said port.

20. In a sander having a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, and blade meansshiftably mounted in said body within said chamber for regulating thedepth of sand in said outlet leg and therethrough the rate of dischargeof sand by gravity from an outlet of said chamber, the improvementcomprising a laterally elongated air outlet in said body below said sandoutlet, said outlets opening beyond said sand chamber onto a mixingchamber in which said sand and air are mixed during a sanding operation,and said air outlet laterally including said sand outlet and beingcoextensive with said mixing chamber.

21. In a sander having a body, a sand chamber in said body and havingconnected angularly related inlet and outlet legs, and blade meansshirtably mounted in said body within said chamber for regulating thedepth of sand in said outlet leg and therethrough the rate of dischargeof sand by gravity from an outlet of said-chamber, the combination of alaterally elongated air outlet in said body below said sand outlet, saidoutlets opening beyond said sand chamber onto a mixing chamber in whichsaid sand and air are mixed during a sanding operation, said air outletlaterally including said sand outlet and being co-extensive with saidmixing chamber, and an air passage in advance of said air outlet andincluding an expansion chamber for reducing the pressure of air passingtneretnrough in advance of injection thereof through said air outletinto said mixing chamber.

References Cited in the file of this patent UNITED STATES PATENTS1,686,454 Johnson Feb. 10, 1914 2,451,878 Savercool Oct. 19, 19482,493,452 Grigg Jan. 3, 1950 2,529,751 White Nov. 14, 1950 2,533,352Tietig Dec. 12, 1950 2,685,379 Moeller Aug. 3 1954 2,725,247 Saari eta1. Nov. 29, 1955 2,773,619 lVloeller Dec. 11, 1956 2,905,355 OrscrSept. 22, 1959 3,020,072 Frantz Feb. 6, 1962

19. A SANDER COMPRISING A BODY, A SAND CHAMBER IN SAID BODY AND HAVINGCONNECTED INLET AND OUTLET LEGS, A SAND OUTLET FROM SAID CHAMBER INTO AMIXING CHAMBER, A SMOOTH-BORED CLEAN-OUT PORT IN A BOTTOM WALL OF SAIDBODY AND OPENING UPWARDLY TOWARD SAID INLET LEG, AN AIR PASSAGE IN SAIDBODY AND HAVING AN OUTLET ONTO SAID MIXING CHAMBER BELOW SAID SANDOUTLET, SAID PASSAGE HAVING PORTIONS OPENING AT SIDES ONTO ANDINTERRUPTING A SIDE OF SAID PORT, AND A CLEAN-OUT PLUG SLIDABLE AXIALLYINTO SAID PORT, SAID PLUG INCLUDING A COMPRESSIBLE SLEEVE SLIDABLE INUNCOMPRESSED CONDITION FREELY INTO SAID PORT AND OVER SAID SIDES OF SAIDPASSAGE PORTIONS, AND MEANS FOR AXIALLY COMPRESSING SAID SLEEVE WITHINSAID PORT AND THEREBY SEALING SAID PORT AND SAID SIDES OF SAID PASSAGEPORTIONS AND LOCKING SAID PLUG IN SAID PORT.